The goal of the proposed research is to increase our knowledge of the role of the kidney in conjugating endogenous compounds, drugs and environmental toxins. The effect of drugs which alter uric acid excretion in man will be studied in the chicken by use of the Sperber technique. In addition, the effects of L-dopa, its intrarenal metabolites and the effect(s) of vanadium on the peritubular and luminal excretory transports of uric acid will be determined by experimentally differentiating between: (a) the renal excretory transport of urate formed during the transfer of a precursor across the renal cell, and (b) the renal excretory transport of preformed urate.